JP6907489B2 - Fine fibrous cellulose-containing material - Google Patents

Description

The present invention relates to a fine fibrous cellulose-containing material having excellent dispersibility of fine particles.

In recent years, due to the substitution of petroleum resources and heightened environmental awareness, materials using reproducible natural fibers have been attracting attention. Among natural fibers, fibrous cellulose having a fiber diameter of 10 to 50 μm, particularly fibrous cellulose (pulp) derived from wood, has been widely used mainly as paper products. Further, as the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known.

Aqueous suspensions or dispersions of fibrous cellulose usually contain several to hundreds of times more solvent than fibrous cellulose. Handling such an aqueous suspension or dispersion as it is has problems of increasing storage space, storage and transportation costs. Therefore, attempts have been made to prepare cellulose concentrates.

For example, Patent Document 1 describes a method for treating an aqueous gel of nanofibril cellulose by removing water from the aqueous gel using an organic solvent miscible with water. In this method, the aqueous gel is maintained as a separation phase, the aqueous gel is introduced in a controlled manner to an organic solvent so as to form a physical entity containing nanofibril cellulose in the separation phase, and the water is exchanged for an organic solvent. , A method of separating a physical entity from an organic solvent. Patent Document 2 describes a bacterial cellulose concentrate containing undissociated bacterial cellulose in a range of 10% by weight or more and less than 75% by weight.

Patent Document 3 describes a cellulose fiber suspension containing cellulose fibers, polyvalent metals and volatile bases, the cellulose fibers having an average fiber diameter of 200 nm or less, and the carboxyl group content of cellulose being 0.1 to 2 mmol / g. The turbid liquid is listed. Patent Document 4 describes a method for producing a dry solid of anion-modified cellulose nanofibers, which comprises adjusting the pH of an aqueous suspension of anion-modified cellulose nanofibers to 9 to 11 and then dehydrating and drying the suspension. Has been done.

Special Table 2014-508228 Japanese Unexamined Patent Publication No. 9-316102 JP-A-2010-168573 JP 2015-134873

As described above, Patent Documents 1 to 4 describe the preparation of cellulose concentrate. However, in particular, when a concentrate of fine fibrous cellulose is used as a thickener, the present inventor is concerned about a decrease in the dispersibility of fine particles (titanium oxide, etc.) in an aqueous medium containing the fine fibrous cellulose. Attention was paid. Further, in order to obtain sufficient dispersibility of the fine particles, it may be necessary to stir for a long time after adding the thickener to the aqueous medium. The study on the concentrate of fine fibrous cellulose from the above viewpoint has not been sufficiently conducted so far.

The present invention has been made in view of the above problems. An object to be solved by the present invention is to provide a fine fibrous cellulose-containing material having good dispersibility of fine particles in an aqueous medium obtained by adding fine fibrous cellulose and then stirring for a short time.

The present inventors have diligently studied to solve the above problems. As a result, in the powdery granular fine fibrous cellulose-containing material, by setting the cumulative medium diameter D50 to a predetermined value or less, the fine fibrous cellulose was added and then stirred for a short time (for example, less than 3 minutes). It has been found that excellent dispersibility of fine particles can be realized in an aqueous medium. The present invention has been completed based on these findings.

That is, according to the present invention, the following invention is provided.
(1) Fine fibrous cellulose containing fine fibrous cellulose having a content of 5% by mass or more, which is powdery and has a cumulative median diameter D50 of 1.2 mm or less. Ingredients.
(2) The fine fibrous cellulose-containing material according to claim 1, wherein the haze value of the following sample is 20% or less: However, the sample contains the fine fibrous cellulose-containing material having a solid content concentration of 0.4% by mass. It is a sample added to pure water so as to be, and stirred with a disperser at 1500 rpm for 5 minutes.
(3) The fine fibrous cellulose-containing material according to (1) or (2), which has a specific surface area of 0.005 m ² / cm ³ or more and 0.5 m ² / cm ^{3 or less.}
(4) The fine fibrous cellulose-containing product according to any one of (1) to (3), which has an angle of repose of 4 to 50 °.
(5) The fine fibrous cellulose-containing product according to any one of (1) to (4), which has a bulk density of 0.1 to 0.5 g / ml.
(6) The fine fibrous cellulose-containing material according to any one of (1) to (5), wherein the cumulative median diameter D50 is 50 μm or more.
(7) The fine fibrous cellulose-containing product according to any one of (1) to (6), which further contains an organic solvent.
(8) The fine fibrous cellulose-containing product according to (7), wherein the organic solvent is isopropyl alcohol.
(9) The fine fibrous cellulose-containing product according to any one of (1) to (8), which further contains water.
(10) The fine fibrous cellulose-containing product according to any one of (1) to (9), wherein the fine fibrous cellulose has an ionic substituent.
(11) The fine fibrous cellulose-containing product according to any one of (1) to (10), wherein the fine fibrous cellulose has a phosphoric acid group.
(12) The fine fibrous cellulose-containing product according to any one of (1) to (11), wherein the amount of the phosphoric acid group in the fine fibrous cellulose is 0.5 mmol / g or more.

According to the fine fibrous cellulose-containing material of the present invention, excellent dispersibility of fine particles can be realized in an aqueous medium obtained by adding the fine fibrous cellulose and then stirring for a short time.

FIG. 1 shows the relationship between the amount of NaOH added to the fiber raw material and the electrical conductivity.

“Parts” and “%” represent proportions based on mass (parts by mass,% by mass) unless otherwise specified. The value regarding the mass of fibers such as cellulose is based on the absolute dry mass (solid content) unless otherwise specified. Further, the numerical range "XY" includes the values at both ends unless otherwise specified. "A or / and B" refers to at least one of A and B, unless otherwise stated, and may be A alone, B alone, or both A and B. It means that it may be.

<Filamentous cellulose raw material>
The fibrous cellulose raw material for obtaining fibrous cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. The pulp is selected from wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached kraft pulp (OKP), and dissolved. Examples include chemical pulp such as pulp (DP). Examples thereof include semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), mechanical pulp such as crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), but are not particularly limited. .. Examples of the non-wood pulp include cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, and cellulose, chitin and chitosan isolated from sea squirts and seaweed, but are not particularly limited. .. Examples of the deinked pulp include deinked pulp made from used paper, but the deinking pulp is not particularly limited. As the pulp of the present embodiment, one of the above may be used alone, or two or more of them may be mixed and used. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refining (defibration) is high, the decomposition of cellulose in the pulp is small, and the fine fibers with a large axial ratio are fine. It is preferable in that fibrous cellulose can be obtained, but it is not particularly limited. Of these, kraft pulp and sulfite pulp are most preferably selected, but are not particularly limited. A sheet containing fine fibrous cellulose of long fibers having a large axial ratio can obtain high strength.

<Ionic substituent>
The fine fibrous cellulose used in the present invention preferably has an ionic substituent, but is not particularly limited thereto.
The ionic substituent may be either an anionic substituent or a cationic substituent, but is preferably an anionic substituent.

The method for introducing an anionic substituent into the fibrous cellulose is not particularly limited, and examples thereof include an oxidation treatment and a treatment with a compound capable of forming a covalent bond with a functional group in the cellulose.

The oxidation treatment is a treatment for converting a hydroxy group in cellulose into an aldehyde group or a carboxy group. Examples of the oxidation treatment include TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment and treatment using various oxidizing agents (sodium chlorite, ozone, etc.). Examples of the oxidation treatment include, but are not limited to, the methods described in Biomacromolecules 8, 2485-2491, 2007 (Saito et al.).

The treatment with the compound can be carried out by introducing the above-mentioned substituent into the fiber raw material by mixing the fiber raw material in a dry state or a wet state with a compound that reacts with the fiber raw material. The heating method is particularly effective because it promotes the reaction at the time of introduction. The heat treatment temperature at the time of introducing the substituent is not particularly limited, but it is preferably in a temperature range in which thermal decomposition or hydrolysis of the fiber raw material is unlikely to occur. For example, from the viewpoint of the thermal decomposition temperature of cellulose, it is preferably 250 ° C. or lower, and from the viewpoint of suppressing the hydrolysis of cellulose, heat treatment is preferably performed at 100 to 170 ° C.

The compound that reacts with the fiber raw material is not particularly limited as long as fine fibers can be obtained and an anionic substituent is introduced.
When an anionic substituent is introduced, examples of the compound that reacts with the fiber raw material include a compound having a phosphoric acid-derived group, a compound having a carboxylic acid-derived group, a compound having a sulfuric acid-derived group, and a sulfonic acid-derived compound. Examples include compounds having a group. From the viewpoint of ease of handling and reactivity with fibers, a compound having at least one selected from the group consisting of a phosphoric acid-derived group, a carboxylic acid-derived group and a sulfuric acid-derived group is preferable. More preferably, but not limited to, these compounds form esters or / and ethers with the fibers.

The amount of the substituent introduced in the anionic substituent-introduced fiber (by the titration method) is not particularly limited, but is preferably 0.005α to 0.11α, more preferably 0.01α to 0.08α per 1 g (mass) of the fiber. When the introduction amount of the substituent is 0.005α or more, the fiber raw material can be easily refined (defibration), and when the introduction amount of the substituent is 0.11α or less, the dissolution of the fiber can be suppressed. However, α is an amount (unit: mmol / g) in which a functional group that can react with a compound that reacts with the fiber material, for example, a hydroxyl group or an amino group is contained in 1 g of the fiber material.

Unless otherwise specified, the amount of substituents introduced on the fiber surface (titration method) can be measured by the following method:
A fine fiber-containing slurry containing a solid content of about 0.04 g by absolute dry mass is separated and diluted to about 50 g with ion-exchanged water. While stirring this solution, measure the change in the value of electrical conductivity when a 0.01 N sodium hydroxide aqueous solution is dropped, and determine the amount of the 0.01 N sodium hydroxide aqueous solution dropped when the value becomes the minimum. , The amount of dropping at the end point of titration. The amount of substituents X on the surface of cellulose is represented by X (mmol / g) = 0.01 (mol / l) × V (ml) / W (g). Here, V: 0.01N aqueous sodium hydroxide solution (ml), W: solid content (g) contained in the fine fibrous cellulose-containing slurry.

In the conductivity titration, the addition of alkali gives the curve shown in FIG. Initially, the electrical conductivity drops sharply (hereinafter referred to as the "first region"). After that, the conductivity begins to increase slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). The boundary point between the second region and the third region is defined by the point at which the second derivative value of the conductivity, that is, the amount of change in the increment (slope) of the conductivity is maximized. That is, three regions appear. Of these, the amount of alkali required in the first region is equal to the amount of strong acid groups in the slurry used for titration, and the amount of alkali required in the second region is equal to the amount of weakly acidic groups in the slurry used for titration. Become equal. When the phosphoric acid group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When it is said, it means the amount of strongly acidic groups.

When the substituent to be introduced is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid and a group derived from sulfuric acid, the amount of the substituent introduced is not particularly limited, but 0. It can be 001 to 5.0 mmol / g. It may be 0.005 to 4.0 mmol / g, or 0.01 to 2.0 mmol / g. When the substituent to be introduced is a phosphoric acid group, the amount of the phosphoric acid group in the fine fibrous cellulose is preferably 0.5 mmol / g or more, preferably 0.5 to 5.0 mmol / g. More preferably, it is 0.5 to 2.0 mmol / g.

When a compound having a phosphoric acid-derived group is used as the compound that reacts with the fiber raw material, it is not particularly limited, but consists of phosphoric acid, polyphosphoric acid, phosphite, phosphonic acid, polyphosphonic acid or salts or esters thereof. At least one selected from the group. Among these, compounds having a phosphoric acid group are preferable, but are not particularly limited because they are low in cost, easy to handle, and can further improve the miniaturization (defibration) efficiency by introducing a phosphoric acid group into the fiber raw material. ..

The compound having a phosphoric acid group is not particularly limited, and examples thereof include phosphoric acid, lithium dihydrogen phosphate which is a lithium salt of phosphoric acid, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. .. Further, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium polyphosphate, which are sodium salts of phosphoric acid, can be mentioned. Further, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium polyphosphate, which are potassium salts of phosphoric acid, can be mentioned. Further, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium polyphosphate and the like, which are ammonium salts of phosphoric acid, can be mentioned.

Of these, phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, and an ammonium salt of phosphoric acid are preferable from the viewpoint of high efficiency of introducing a phosphoric acid group and easy industrial application, and sodium dihydrogen phosphate. , Disodium hydrogen phosphate is more preferable, but it is not particularly limited.

Further, the compound is preferably used as an aqueous solution because of the uniformity of the reaction and the high efficiency of introducing a group derived from phosphoric acid, but it is not particularly limited. The pH of the aqueous solution of the compound is not particularly limited, but is preferably 7 or less because of the high efficiency of introducing a phosphate group. From the viewpoint of suppressing the hydrolysis of fibers, pH 3 to 7 is particularly preferable, but is not particularly limited.

When a compound having a group derived from a carboxylic acid is used as a compound that reacts with a fiber raw material, the compound is not particularly limited, but is composed of a group consisting of a compound having a carboxy group, an acid anhydride of a compound having a carboxy group, and derivatives thereof. At least one selected.

The compound having a carboxy group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. ..

The acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Be done.

The derivative of the compound having a carboxy group is not particularly limited, and examples thereof include an imide of an acid anhydride of a compound having a carboxy group and a derivative of an acid anhydride of a compound having a carboxy group. The imide of the acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinateimide, and phthalateimide.

The derivative of the acid anhydride of the compound having a carboxy group is not particularly limited. For example, at least a part of hydrogen atoms of the acid anhydride of a compound having a carboxy group, such as dimethylmaleic anhydride, diethylmalic anhydride, diphenylmaleic anhydride, etc., is a substituent (for example, an alkyl group, a phenyl group, etc.). ) Replaced by).

Among the compounds having a group derived from the carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferable because they are easily applied industrially and easily gasified, but are not particularly limited.

When a compound having a sulfuric acid-derived group is used as the compound that reacts with the fiber raw material, it is not particularly limited, but is at least one selected from the group consisting of anhydrous sulfuric acid, sulfuric acid, and salts and esters thereof. Among these, sulfuric acid is preferable, but is not particularly limited, because it is low in cost and can further improve the miniaturization (defibration) efficiency by introducing a sulfuric acid group into the fiber raw material.

When a cationic substituent is introduced, examples of the compound that reacts with the fiber raw material include compounds having a group derived from an onium salt such as an ammonium salt, a phosphonium salt, and a sulfonium salt. Specific examples thereof include compounds having a group containing ammonium, phosphonium, and sulfonium, such as a primary ammonium salt, a secondary ammonium salt, a tertiary ammonium salt, and a quaternary ammonium salt. Groups derived from quaternary ammonium salts and groups derived from phosphonium salts can be mentioned from the viewpoint of ease of handling and reactivity with fibers. The amount of the cationic substituent introduced can be measured by using, for example, elemental analysis.

In the present embodiment, for example, a cationic substituent can be introduced into the fiber raw material by adding a cationizing agent and an alkaline compound to the fiber raw material and reacting them. As the cationizing agent, one having a quaternary ammonium group and a group that reacts with the hydroxy group of cellulose can be used. Examples of the group that reacts with the hydroxy group of cellulose include an epoxy group, a functional group having a halohydrin structure, a vinyl group, a halogen group and the like.
Specific examples of the cationizing agent include glycidyltrialkylammonium halides such as glycidyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride, or halohydrin-type compounds thereof.

The alkaline compound used in the cationization step contributes to the promotion of the cationization reaction. The alkaline compound may be an inorganic alkaline compound or an organic alkaline compound.

Examples of the inorganic alkali compound include alkali metal hydroxide or alkaline earth metal hydroxide, alkali metal carbonate or alkaline earth metal carbonate, alkali metal phosphate or alkaline earth metal phosphoric acid. Salt is mentioned.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of hydroxides of alkaline earth metals include calcium hydroxide.
Examples of alkali metal carbonates include lithium carbonate, lithium hydrogencarbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, and sodium hydrogencarbonate. Examples of carbonates of alkaline earth metals include calcium carbonate.
Examples of the alkali metal phosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of the phosphate of the alkaline earth metal include calcium phosphate and calcium hydrogen phosphate.

Examples of the organic alkaline compound include ammonia, aliphatic amines, aromatic amines, aliphatic ammonium, aromatic ammonium, heterocyclic compounds and their hydroxides, carbonates, phosphates and the like. Can be mentioned.
Ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentano, diaminohexane;
Cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide;
Pyridine, N, N-dimethyl-4-aminopyridine;
Ammonium carbonate, ammonium hydrogen carbonate, diammonium hydrogen phosphate, etc.
The above-mentioned alkaline compound may be used alone or in combination of two or more.

Among the above alkaline compounds, sodium hydroxide and potassium hydroxide are preferable because the cationization reaction is more likely to occur and the cost is low. The amount of the alkaline compound varies depending on the type of the alkaline compound, but is, for example, in the range of 1 to 10% by mass with respect to the absolute dry mass of pulp.

Since the cationizing agent and the alkaline compound can be easily added to the pulp, it is preferable to make a solution. The solvent used in the solution formation may be either water or an organic solvent, but a polar solvent (a polar organic solvent such as water or alcohol) is preferable, and an aqueous solvent containing at least water is more preferable.

In this production method, the amount of solvent substance per 1 g of absolute dry mass of pulp at the start of the cationization reaction is preferably 5 to 150 mmol. The amount of substance of the solvent is more preferably 5 to 80 mmol, and even more preferably 5 to 60 mmol. In order to keep the pulp content during the cationization reaction within the above range, for example, pulp having a high content (that is, a low water content) may be used. Further, it is preferable to reduce the amount of the solvent contained in the solution of the cationizing agent and the alkaline compound.

The reaction temperature in the cationization step is preferably in the range of 20 to 200 ° C, more preferably in the range of 40 to 100 ° C. When the reaction temperature is not less than the lower limit value, sufficient reactivity can be obtained, and when it is not more than the upper limit value, the reaction can be easily controlled. It also has the effect of suppressing the coloring of pulp after the reaction. The time of the cationization reaction varies depending on the type of pulp and cationizing agent, pulp content, reaction temperature and the like, but is usually in the range of 0.5 to 3 hours.

The cationization reaction may be carried out in a closed system or an open system. Further, the solvent may be evaporated during the reaction so that the amount of the solvent substance per 1 g of the absolute dry mass of the pulp at the end of the reaction may be lower than that at the start of the reaction.

By introducing an ionic substituent into the fiber raw material, the dispersibility of the fiber in the solution can be improved and the defibration efficiency can be improved.

<Miniaturization treatment of fibrous cellulose>
The fine fibrous cellulose slurry can be produced by subjecting the fibrous cellulose to a micronization (defibration) treatment.

During the micronization process, the fibrous cellulose is dispersed in a solvent.
Specific examples of the solvent include water, an organic solvent alone, and a mixture of water and an organic solvent. The organic solvent is not particularly limited as long as the intended relative permittivity can be secured. For example, alcohols, polyhydric alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like can be mentioned. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol and glycerin. Examples of ketones include acetone, methyl ethyl ketone and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, ethylene glycol mono t-butyl ether and the like. Only one kind of organic solvent may be used, or two or more kinds may be used. Of the above, the solvent is preferably water.

The dispersion concentration of the fibrous cellulose in the solvent is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass. This is because if the dispersion concentration is 0.1% by mass or more, the efficiency of the defibration treatment is improved, and if it is 20% by mass or less, blockage in the defibration treatment apparatus can be prevented.

The defibrating processing device is not particularly limited. Examples thereof include a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, an ultra-high pressure homogenizer, a clear mix, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, and a conical refiner. In addition, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, a beater, or a wet pulverizer can be appropriately used.

By the micronization treatment, a fine fibrous cellulose slurry is obtained. The average fiber width of the obtained fine fibrous cellulose is not particularly limited, but can be, for example, 1 to 1000 nm, preferably 2 to 1000 nm, more preferably 2 to 500 nm, and further preferably 3 to 100 nm. When the average fiber width of the fine fibers is 1 nm or more, the dissolution of the molecules in water is suppressed, so that the physical characteristics (strength, rigidity, dimensional stability) of the fine fibers are sufficiently exhibited. On the other hand, when the average fiber width is 1000 nm or less, the features (high transparency, high elastic modulus, low linear expansion coefficient, flexibility) as fine fibers are easily exhibited. The obtained fine fibrous cellulose dispersion may contain fibrous cellulose having a fiber width of more than 1000 nm, but preferably does not contain fibrous cellulose having a fiber width of more than 1000 nm. The fine fibrous cellulose is, for example, a monofibrous cellulose having a fiber width of 1000 nm or less.

In applications where transparency is required for fine fibers, if the average fiber width is 30 nm or less, it approaches 1/10 of the wavelength of visible light, and when combined with a matrix material, visible light is refracted and scattered at the interface. It tends to be difficult to occur and highly transparent. Therefore, the average fiber width is not particularly limited, but is preferably 2 nm to 30 nm, more preferably 2 to 20 nm. The composite obtained from the fine fibers as described above generally has a high strength because it has a dense structure, and high transparency can be obtained because it scatters less visible light.

The average fiber width is measured as follows. A fine fiber-containing slurry having a concentration of 0.05 to 0.1% by mass is prepared, and the slurry is cast on a hydrophilized carbon film-coated grid to prepare a sample for TEM observation. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, 20000 times, or 50,000 times depending on the width of the constituent fibers. However, the sample, observation conditions and magnification should be adjusted so as to satisfy the following conditions.
(1) A straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The width of the fiber intersecting the straight line X and the straight line Y is visually read with respect to the observation image satisfying the above conditions. In this way, at least three sets of images of the non-overlapping surface portions are observed, and the widths of the fibers intersecting the straight lines X and Y are read for each image. In this way, at least 20 fibers × 2 × 3 = 120 fibers are read. The average fiber width is the average value of the fiber widths read in this way.

The fiber length is not particularly limited, but is preferably 0.1 μm or more. When the fiber length is 0.1 μm or more, it is preferable that the tear strength of the sheet is sufficient when the sheet described later is produced. The fiber length can be obtained by image analysis of TEM, SEM, and AFM. The fiber length is a fiber length that occupies 30% by mass or more of the fine fibers.

The axial ratio of the fibers (fiber length / fiber width) is not particularly limited, but is preferably in the range of 20 to 10,000. When the axial ratio is 20 or more, it is preferable in that a fine fiber-containing sheet can be easily formed. When the axial ratio is 10,000 or less, the slurry viscosity is low, which is preferable.

By the micronization treatment, a fine fibrous cellulose slurry is obtained. The concentration of the fine fibrous cellulose here is, for example, 0.1 to 20% by mass, may be 0.2 to 10% by mass, or may be 0.5 to 10% by mass.

<Dehydration and powdering>
By subjecting the fine fibrous cellulose slurry obtained above to dehydration treatment and powder granulation treatment, a fine fibrous cellulose-containing material having a fine fibrous cellulose content of 5% by mass or more according to the present invention is prepared. be able to. That is, according to the present invention, a step of gelling a diluted solution containing fine fibrous cellulose, a step of obtaining a concentrate containing fine fibrous cellulose from the gelled product obtained above, and a step of heating the concentrate. Also provided is a method for producing a fine fibrous cellulose-containing material of the present invention, which comprises a step of crushing the concentrate.

The above gelation step can be performed by adding a concentrating agent or a solvent to the diluted solution containing fine fibrous cellulose, but is not particularly limited. The step of obtaining a concentrate containing fine fibrous cellulose from the gelled product can be performed by filtering the gelled product and then squeezing it, but the process is not particularly limited. The step of heating the concentrate can be performed by heating in an oven or the like, but is not particularly limited.

The method of dehydration treatment is not particularly limited, and examples thereof include the following methods.
(1) A concentrate is added to a diluted solution containing fine fibrous cellulose to gel it, and after filtration, it is squeezed to obtain a concentrate. The concentrate is treated with an acid and then with an alkali to give the concentrate. A solvent is added to the above concentrate and filtered to obtain a concentrate, and the obtained concentrate is heated in an oven or the like.

(2) A concentrate is added to a diluted solution containing fine fibrous cellulose to gel it, and after filtration, it is squeezed to obtain a concentrate. The obtained concentrate is heated in an oven or the like.

(3) A concentrate is added to a diluted solution containing fine fibrous cellulose to gel it, and after filtration, it is squeezed to obtain a concentrate. The concentrate is treated with an alkali to obtain a concentrate. A solvent is added to the concentrate and filtered to obtain a concentrate. The step of adding a solvent and filtering to obtain a concentrate may be performed twice or more. The obtained concentrate is heated in an oven or the like.

(4) A solvent is added to a diluted solution containing fine fibrous cellulose to gel it, and a residue is obtained by filtration. The solvent is added to this residue again, and the residue is obtained by filtration. From the viewpoint of improving the dispersibility of the fine particles, it is preferable that the above-mentioned solvent addition and filtration operations are performed twice or more. The obtained filtration residue is heated in an oven or the like.

Examples of the above-mentioned concentrate include acids, alkalis, salts of polyvalent metals, cationic surfactants, anionic surfactants, cationic polymer flocculants, and anionic polymer flocculants. Above all, the concentrate is preferably a salt of a polyvalent metal. Specific examples of salts of polyvalent metals will be described later in the present specification.

It is preferable to carry out the filtration treatment after adding the concentrate, but the present invention is not particularly limited. Further, it is preferable to perform a compression step after the filtration treatment step, but the present invention is not particularly limited. By providing the compression step, the water content in the concentrate can be adjusted to a preferable range.
As the squeezing device, a general press device such as a belt press, a screw press, or a filter press can be used, and the device is not particularly limited.
The filter medium used is not particularly limited, but stainless steel, filter paper, polypropylene, nylon, polyethylene, polyester and the like can be used. Polypropylene is preferable because an acid may be used.
The lower the air permeability of the filter medium, the higher the yield. Therefore, the yield is 30 cm3 / cm2 · sec or less, more preferably 10 cm3 / cm2 · sec or less, and further preferably 1 cm3 / cm2 · sec or less.
If the concentration of the raw material to be used in the pressing step is low, the amount of the dehydrated filtrate increases and the dehydration step takes a long time. Therefore, the concentration is 0.5% or more, more preferably 1% or more, still more preferably 2% or more. ..
The pressure at the time of squeezing is 0.2 MPa or more, more preferably 0.4 MPa or more.

It is also possible to provide a step of treating the concentrate obtained above with an acid and / or a step of treating with an alkali. The acid treatment step is preferably provided before and after the above filtration treatment step, and is preferably provided after the filtration treatment step.

Acids that can be used in the process of treating with acid will be described later in this specification. Specifically, it is preferable to immerse the concentrate obtained in the above-mentioned step in an acidic liquid containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less. By setting the concentration of the acidic liquid in the above range, deterioration due to decomposition of cellulose can be suppressed.

The alkalis that can be used in the process of treating with alkalis will be described later in this specification. Specifically, it is preferable to immerse the concentrate obtained in the above-mentioned step or the concentrate treated with an acid in an alkaline liquid containing an alkali. The concentration of the alkaline liquid used is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less. By setting the concentration of the alkaline liquid in the above range, deterioration due to decomposition of cellulose can be suppressed.

Filtration is preferably performed after the above-mentioned acid treatment step and alkali treatment step. In this filtration treatment step, a compression step may be further performed.

In the present invention, a drying step may be further provided. The drying step is preferably an oven drying step, and for example, it is preferable to perform drying in an oven set at 30 to 70 ° C. for 1 to 60 minutes.

In the step of crushing the concentrate, a cutter mill, a hammer mill, a pin mill, a ball mill, a jet mill, a mixer and the like are used as the crusher, but the crusher is not particularly limited. Grind to the extent that a sieve with a mesh size of 2 mm is passed through almost completely. More preferably, a sieve having an opening of 425 μm is pulverized so as to pass through almost all of the sieves.

<Fine fibrous cellulose-containing material>
The fine fibrous cellulose-containing material of the present invention is a fine fibrous cellulose-containing material having a fine fibrous cellulose content of 5% by mass or more, which is powdery and has a cumulative medium diameter D50 of 1.2 mm. It is as follows. The cumulative median diameter D50 can be controlled by appropriately adjusting, for example, a method for preparing the fine fibrous cellulose-containing material, a method for concentrating the fine fibrous cellulose, a method for pulverizing the concentrate, and the like.

In the present invention, the content of fine fibrous cellulose is 5% by mass or more. The upper limit of the content of the fine fibrous cellulose is not particularly limited and may be 100% by mass or less than 100% by mass, preferably the content of the fine fibrous cellulose is 99% by mass or less. The upper limit of the content of the fine fibrous cellulose may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, but is not particularly limited. .. The lower limit of the content of the fine fibrous cellulose is not particularly limited as long as it is 5% by mass or more, but it may be 10% by mass or more, 15% by mass or more, or 20% by mass or more.

The fine fibrous cellulose-containing material of the present invention is powdery and granular. The powdery granular substance means a substance composed of a powdery substance and / or a granular substance. A powdery substance is smaller than a granular substance. Generally, the powdery substance refers to fine particles having a particle size of 1 nm or more and less than 0.1 mm, and the granular substance refers to particles having a particle size of 0.1 to 10 mm, but is not particularly limited. It should be noted that the powder granules are not necessarily spherical. The particle size of the powder or granular material in the specification of the present application can be measured by the following method. The particle size of the powder or granular material in the present specification is a value measured using a laser diffraction / scattering type particle size distribution measuring device (Microtrac3300EXII, Nikkiso Co., Ltd.).

The cumulative median diameter D50 of the fine fibrous cellulose-containing material of the present invention may be 1.2 mm or less, and the lower limit thereof is not particularly limited, but the cumulative median diameter D50 is preferably 50 μm or more. The cumulative median diameter D50 may be 100 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, 500 μm or more, 600 μm or more, or 700 μm or more. The cumulative median diameter D50 may be 1000 μm or less, 900 μm or less, or 800 μm or less.

By setting the cumulative median diameter within the above range, the surface area of the particles contained in the fine fibrous cellulose-containing material can be set within an appropriate range, the contact area with a dispersion medium such as water can be increased, and redispersion can be achieved. You can improve your sex. Further, by setting the cumulative median diameter within the above range, it is possible to suppress unintended agglomeration of particles, and it is possible to enhance redispersibility. In this way, it is possible to realize good dispersibility of fine particles even in an aqueous medium obtained by adding a fine fibrous cellulose-containing substance and stirring for a short time.

The volume average diameter of the fine fibrous cellulose-containing material of the present invention is preferably 20 μm or more and 1500 μm or less, more preferably 50 μm or more and 1200 μm or less, but is not particularly limited.
The number average diameter of the fine fibrous cellulose-containing material of the present invention is preferably 10 μm or more and 100 μm or less, more preferably 20 μm or more and 500 μm or less, but is not particularly limited.
The area average diameter of the fine fibrous cellulose-containing material of the present invention is preferably 10 μm or more and 1000 μm or less, more preferably 30 μm or more and 800 μm or less, but is not particularly limited.

The haze value of the sample obtained by adding the fine fibrous cellulose-containing material of the present invention to pure water so that the solid content concentration was 0.4% by mass and stirring with a disperser at 1500 rpm for 5 minutes was 20%. The following is preferable, but the present invention is not particularly limited. The lower limit of the haze value is not particularly limited, but is preferably 0.1% or more, more preferably 0.2% or more, and further preferably 0.5% or more. In the present invention, when the haze value satisfies the above conditions, the dispersibility of the fine particles in the aqueous medium containing the fine fibrous cellulose can be further improved.
The disperser is not particularly limited as long as it is a general disperser, but a stirrer such as a homomixer or a three-one motor is used.

The fine fibrous cellulose-containing material of the present invention preferably has a specific surface area of 0.005 m ² / cm ³ or more and 0.5 m ² / cm ³ or less, but is not particularly limited. The specific surface area is more preferably not more than 0.008 m ² / cm ³ or more 0.5 m ² / cm ^3, still more preferably not more than 0.04 m ² / cm ³ or more 0.2m ² / cm ^3.
By setting the specific surface area within the above range, a sufficient contact area with the solvent is secured when the specific surface area is added to the solvent and redispersed, and the water is uniformly hydrated. As a result, the fine fibrous cellulose in the solvent is uniformly dispersed, and the dispersibility of the fine particles added into the system can be improved. On the other hand, if the specific surface area is too large, the bulk density is lowered, which causes deterioration of handleability and powdering.
The specific surface area, the angle of repose, the bulk density, etc., which will be described later, can be controlled by appropriately adjusting, for example, a method for preparing and concentrating the fine fibrous cellulose-containing material, a method for crushing the concentrate, and the like. Is.

The angle of repose of the fine fibrous cellulose-containing material of the present invention is preferably 4 to 50 °, but is not particularly limited. The angle of repose is more preferably 5 to 45 °, even more preferably 5 to 40 °, and particularly preferably 10 to 40 °. The angle of repose is a parameter involved in the fluidity of the fine fibrous cellulose-containing material. The smaller the angle of repose, the higher the fluidity of the fine fibrous cellulose-containing material tends to be. However, even if the angle of repose is small, if a large amount of fine particles are present in the fine fibrous cellulose-containing material, the powder The fluidity (feedability) deteriorates due to the occurrence of dance.

The angle of repose is measured using an angle of repose measuring device (AS ONE). Specifically, 100 ml of the fine fibrous cellulose-containing material is charged into the chute of the angle of repose measuring device, the chute opening is opened, and the fine fibrous cellulose-containing material is dropped to the lower part. Then, the angle formed by the slope and the horizontal plane of the fine fibrous cellulose-containing material after the fall is measured and used as the angle of repose of the fine fibrous cellulose-containing material.

The bulk density of the fine fibrous cellulose-containing material of the present invention is preferably 0.1 to 0.5 g / ml, more preferably 0.1 to 0.4 g / ml, and 0.1 to 0.1. It is more preferably 0.3 g / ml, but it is not particularly limited. The larger the bulk density, the smaller the particle size of the particles constituting the fine fibrous cellulose-containing material tends to be. Therefore, the contact area with a dispersion medium such as water can be increased, and the redispersibility is enhanced. On the other hand, if the bulk density is too large, the particles in the fine fibrous cellulose-containing material may cause unintended aggregation, which is not preferable. On the other hand, if the bulk density is too small, the shape of the particles becomes non-uniform and the particle size tends to be large, so that the fluidity (feedability) deteriorates.

The bulk density is measured using an angle of repose measuring device (AS ONE). Specifically, 100 ml of fine fibrous cellulose-containing material is charged into the chute of the angle of repose measuring device, the chute opening is opened, the fine fibrous cellulose-containing material is dropped to the lower part, and the container installed underneath (full volume ∨). = 50 ml) and fill it. Next, the raised portion of the raised fine fibrous cellulose-containing material is horizontally cut to fill the volume. The mass of the fine fibrous cellulose-containing material remaining in the container is weighed, and the bulk density (g / ml) is calculated from the following formula.
Bulk density (g / ml) = mass of powder (g) / volume of powder (ml)

When an organic solvent is used as the solvent in the above dehydration treatment, the fine fibrous cellulose-containing material of the present invention obtained by the above treatment may further contain an organic solvent. When water is used as the solvent, the fine fibrous cellulose-containing material of the present invention obtained by the above treatment may further contain water.

Examples of the solvent used in the dehydration treatment include an organic solvent or a mixture of an organic solvent and water. Examples of the organic solvent include alcohols, polyhydric alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol and glycerin. Examples of ketones include acetone, methyl ethyl ketone and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, ethylene glycol mono t-butyl ether and the like. Only one kind of organic solvent may be used, or two or more kinds may be used. Among the above, the solvent is preferably alcohols or a mixture of alcohols and water. The solvent is more preferably isopropyl alcohol, or a mixture of isopropyl alcohol and water.

When the fine fibrous cellulose-containing material of the present invention contains alcohols and water, the mass ratio of the contents of alcohols and water is preferably 1/5 to 5/1, and more preferably. It is 1/3 to 1/1, but is not particularly limited. The above alcohols are preferably isopropyl alcohol.

When a concentrating agent is used in the above dehydration treatment, the fine fibrous cellulose-containing material of the present invention obtained by the above treatment may further contain a concentrating agent.
Examples of the concentrating agent include salts of polyvalent metals, cationic surfactants, anionic surfactants, cationic polymer flocculants, anionic polymer flocculants, and the like, but are not particularly limited. When a salt of a polyvalent metal is used as the concentrate, the fine fibrous cellulose-containing material of the present invention may further contain the polyvalent metal. Examples of the polyvalent metal include, but are not limited to, aluminum, calcium, magnesium and the like. Examples of the salt of the polyvalent metal include aluminum sulfate (sulfate band), polyaluminum chloride, calcium chloride, aluminum chloride, magnesium chloride, calcium sulfate, magnesium sulfate and the like, but are not particularly limited.

When the fine fibrous cellulose-containing material of the present invention contains a polyvalent metal, the content thereof is not particularly limited, but is preferably 5 ppm or more and 1000 ppm or less, and more preferably 10 ppm or more and 100 ppm or less. In the fine fibrous cellulose-containing material, the content of the polyvalent metal can be less than 5 ppm, and it is also possible to adopt an embodiment that does not contain the polyvalent metal.

When an acid is used in the above dehydration treatment, the fine fibrous cellulose-containing material of the present invention obtained by the above treatment may further contain an acid.
As the acid, for example, an inorganic acid, a sulfonic acid, a carboxylic acid or the like can be used. Examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, phosphoric acid, boric acid and the like. Examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. Examples of the carboxylic acid include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, tartaric acid and the like.

When the fine fibrous cellulose-containing material of the present invention contains an acid, the content thereof is not particularly limited, but may be 0.01% by mass or more and 0.14% by mass or less with respect to the mass of the fine fibrous cellulose. preferable. In the fine fibrous cellulose-containing material, the acid content can be less than 0.01% by mass, and an acid-free mode can be adopted.

When an alkali is used in the above dehydration treatment, the fine fibrous cellulose-containing material of the present invention obtained by the above treatment may further contain an alkali.
The alkali may be either an inorganic alkali or an organic alkali.
Examples of the inorganic alkali include, but are not limited to, the following. Lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, calcium carbonate, calcium phosphate, calcium hydrogen phosphate.
Examples of the organic alkali include, but are not limited to, the following.
Ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentano, diaminohexane;
Cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide;
Pyridine, N, N-dimethyl-4-aminopyridine, etc.

When the fine fibrous cellulose-containing material of the present invention contains an alkali, the content thereof is not particularly limited, but is preferably 0.01% by mass or more and 2% by mass or less with respect to the mass of the fine fibrous cellulose. The content is more preferably 0.2% by mass or less, and further preferably 0.02% by mass or less. In the fine fibrous cellulose-containing material, the alkali content can be less than 0.01% by mass, and an alkali-free aspect can be adopted.

In the fine fibrous cellulose-containing material of the present invention, when the fine fibrous cellulose is anion-modified, it is desirable that the counterion of the functional group is sodium ion. By using sodium ions, the fine fibrous celluloses repel each other and are less likely to cause aggregation.

The fine fibrous cellulose-containing material of the present invention preferably has a pH of the following sample of 7 or more and 11 or less, and more preferably a pH of the following sample of 8 or more and 10.5 or less, but is not particularly limited. The sample is a sample in which the fine fibrous cellulose-containing material is added to pure water so that the solid content concentration becomes 0.4% by mass, and the mixture is stirred with a disperser at 1500 rpm for 5 minutes.
When the pH of the sample is 7 or more, the counterion of the functional group of the fine fibrous cellulose becomes sodium ion, and the fine fibrous celluloses electrostatically repel each other and are easily dispersed in the solvent.
By setting the pH of the sample to 11 or less, the alkali concentration in the system can be suppressed, and the dispersibility of the fine fibrous cellulose in the solvent due to the electrostatic repulsive force can be improved.

<Redispersion of fine fibrous cellulose-containing material>
By resuspending the fine fibrous cellulose-containing material of the present invention in a solvent, a fine fibrous cellulose redispersion can be obtained.

The type of solvent used to obtain the fine fibrous cellulose-containing material is not particularly limited. Specific examples of the solvent include water, an organic solvent alone, and a mixture of water and an organic solvent. Examples of the organic solvent include alcohols, polyhydric alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol and glycerin. Examples of ketones include acetone, methyl ethyl ketone and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, ethylene glycol mono t-butyl ether and the like. Only one kind of organic solvent may be used, or two or more kinds may be used. Among the above, the solvent is preferably a mixture of alcohols and water, a mixture of ethers and water, or a mixture of DMSO and water.

The fine fibrous cellulose can be redispersed by a conventional method. For example, a step of adding the above-mentioned solvent to the fine fibrous cellulose-containing material of the present invention to prepare a liquid containing the fine fibrous cellulose, and a step of preparing the fine fibrous cellulose in the liquid containing the fine fibrous cellulose. Redispersion can be performed by the step of dispersing.

When a solvent is added to the fine fibrous cellulose-containing material of the present invention to prepare a liquid containing fine fibrous cellulose, the content of the fine fibrous cellulose is 0.1% by mass to 10% by mass with respect to the entire liquid. Is preferable. It is more preferable that the content of the fine fibrous cellulose is 0.2% by mass to 3% by mass with respect to the fine fibrous cellulose-containing liquid. When the content is 0.1% by mass or more, the dispersion stability of the fine fibrous cellulose is high, and when the content is 10% by mass or less, the viscosity of the fine fibrous cellulose is not too high and the handling is easy. It will be relatively easy. The content of fine fibrous cellulose can be adjusted by the amount of solvent added, and the larger the amount of solvent added, the lower the content of fine fibrous cellulose.

As the disperser used in the step of dispersing the fine fibrous cellulose, the same disperser as the defibration treatment device described in the above <Filamentous cellulose refining treatment> can be used.

In the fine fibrous cellulose redispersion obtained as described above, the concentration of the fine fibrous cellulose is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and more preferably 1% by mass. % Or more, more preferably 3% by mass or more. The upper limit of the concentration of the fine fibrous cellulose is not particularly limited, but is generally 10% by mass or less. By keeping the concentration of the fine fibrous cellulose within the above range, the handling at the time of coating is improved and the dispersion stability is excellent. The dispersibility can be evaluated by visually observing the liquid immediately after performing the dispersion treatment with a homodisper or the like and checking whether or not precipitation is observed.

<Other ingredients>
The fine fibrous cellulose-containing material of the present invention may contain a surfactant. By including the surfactant, the surface tension can be reduced, the wettability to the process substrate can be enhanced, and the fine fibrous cellulose-containing sheet can be formed more easily.

As the surfactant, a nonionic surfactant, an anionic surfactant, and a cationic surfactant can be used. When cellulose is anionic, nonionic surfactants and anionic surfactants are preferable, and when cellulose is cationic, nonionic surfactants and cationic surfactants are preferable.

The fine fibrous cellulose-containing material of the present invention can also be prepared by mixing at least one kind of fibers other than fine fibrous cellulose (hereinafter referred to as "additional fibers"). Examples of the additional fiber include, but are not limited to, semi-synthetic fiber and regenerated fiber such as inorganic fiber, organic fiber, and synthetic fiber. Examples of the inorganic fiber include, but are not limited to, glass fiber, rock fiber, metal fiber and the like. Examples of the organic fiber include, but are not limited to, fibers derived from natural products such as cellulose, carbon fiber, pulp, chitin, and chitosan. Examples of synthetic fibers include, but are not limited to, nylon, vinylon, vinylidene, polyester, polyolefin (for example, polyethylene, polypropylene, etc.), polyurethane, acrylic, polyvinyl chloride, aramid, and the like. Examples of the semi-synthetic fiber include, but are not limited to, acetate, triacetate, and promix. Examples of the recycled fiber include, but are not limited to, rayon, cupra, polynosic rayon, lyocell, tencel and the like. The additional fiber can be subjected to a treatment such as a chemical treatment or a defibration treatment, if necessary. When the additional fiber is subjected to a treatment such as a chemical treatment or a defibration treatment, the additional fiber can be mixed with the fine fiber and then subjected to a treatment such as a chemical treatment or a defibration treatment, or the additional fiber is chemically treated or defibrated. It is also possible to mix with fine fibers after undergoing treatment such as treatment. When the additional fibers are mixed, the amount of the additional fibers added in the total amount of the fine fibers and the additional fibers is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30. It is less than mass%. Particularly preferably, it is 20% by mass or less.

A hydrophilic polymer may be added to the fine fibrous cellulose-containing material of the present invention. The hydrophilic polymer is not particularly limited. Examples thereof include polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.), casein, dextrin, starch, modified starch and the like. In addition, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.) can be mentioned. Further, polyethylene oxide, polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylates, polyacrylamide, acrylic acid alkyl ester copolymer, urethane-based copolymer and the like can be mentioned.

Further, a hydrophilic low molecular weight compound can be used instead of the hydrophilic polymer. The hydrophilic low molecular weight compound is not particularly limited. For example, glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol and the like can be mentioned. When a hydrophilic polymer or a hydrophilic low molecular weight compound is added, the amount added is not particularly limited. For example, it is 1 to 200 parts by mass, preferably 1 to 150 parts by mass, more preferably 2 to 120 parts by mass, and further preferably 3 to 100 parts by mass with respect to 100 parts by mass of the solid content of the fine fiber.

<Use>
The use of the fine fibrous cellulose-containing material according to the present invention is not particularly limited. As an example, a film can be formed using a fine fibrous cellulose redispersion slurry and used as various films. As another example, the fine fibrous cellulose redispersed slurry can be used as a thickener in various applications (eg, additives to foods, cosmetics, cement, paints, inks, etc.). Further, it can be mixed with a resin or an emulsion and used as a reinforcing material.

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Production Example 1: Production of fine fibrous cellulose (CNF) (1) Preparation of CNF1:
A phosphorylation reagent was prepared by dissolving 100 g of urea, 55.3 g of sodium dihydrogen phosphate dihydrate, and 41.3 g of disodium hydrogen phosphate in 109 g of water.
A sheet of dried softwood bleached kraft pulp was treated with a cutter mill and a pin mill into cotton-like fibers. 100 g of this cotton-like fiber was taken by absolute dry mass, and after spraying the phosphorylation reagent evenly with a spray, it was kneaded by hand to obtain a chemical-impregnated pulp.
The obtained chemical-impregnated pulp was heat-treated for 80 minutes in a blower dryer equipped with a damper heated to 140 ° C. to obtain phosphorylated pulp.
100 g of the obtained phosphorylated pulp was taken out by the pulp mass, 10 L of ion-exchanged water was poured, and the mixture was stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet. The process was repeated twice. The dehydration sheet obtained here is referred to as a dehydration sheet A.

Next, the dehydrated sheet obtained above was diluted with 10 L of ion-exchanged water, and a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a pulp slurry having a pH of 12 to 13.
Then, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then 10 L of ion-exchanged water was poured, stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet. The steps were repeated twice.
A 2% slurry was prepared and passed 10 times at a pressure of 245 MPa with a wet atomizer (“Ultimizer” manufactured by Sugino Machine Limited) to obtain CNF1.

-Amount of substituents introduced The amount of phosphoric acid groups introduced into the above dehydrated sheet A was measured by the following titration method.
[Measurement of substituent introduction amount (phosphate group introduction amount)]
The amount of substituents introduced is the amount of phosphoric acid groups introduced into the fiber raw material, and the larger this value is, the more phosphoric acid groups are introduced. The amount of the substituent introduced was measured by diluting the target fine fibrous cellulose with ion-exchanged water so that the content was 0.2% by mass, treating with an ion-exchange resin, and titrating with an alkali. In the treatment with an ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 is added to a slurry containing 0.2 mass% fibrous cellulose and shaken for 1 hour. Was done. Then, the resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm. In the titration using alkali, the change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1 N aqueous sodium hydroxide solution to the fibrous cellulose-containing slurry after ion exchange. That is, the amount of alkali (mmol) required in the first region of the curve shown in FIG. 1 was divided by the solid content (g) in the slurry to be titrated to obtain the amount of substituent introduced (mmol / g).

(2) Preparation of CNF2 In the preparation of CNF1, CNF2 was prepared in the same manner as the preparation of CNF1 except that the heat treatment was performed for 160 minutes instead of the heat treatment for 80 minutes in the blower dryer.

(3) Preparation of CNF3 Undried softwood bleached kraft pulp equivalent to 200 g of dry mass, 2.5 g of TEMPO, and 25 g of sodium bromide were dispersed in 1500 ml of water. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so that the amount of sodium hypochlorite was 5.0 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 to 11, and the reaction was terminated when no change was observed in the pH.
Then, this pulp slurry was dehydrated to obtain a dehydrated sheet, and then 10 L of ion-exchanged water was added. Next, the steps of stirring and uniformly dispersing and then filtering and dehydrating to obtain a dehydrated sheet were repeated twice.
After diluting with ion-exchanged water so that the concentration becomes 0.5% by mass, defibration is performed for 30 minutes under the condition of 21500 rpm using a defibration treatment device (Clearmix-2.2S manufactured by M-Technique). Treatment was performed to obtain CNF3.

The amounts of substituents of CNF1 to CNF3 are shown in Table 1 below.

<Measurement of fiber width>
The fiber widths of CNF1 to CNF3 were measured by the following methods.
The supernatant of the defibrated pulp slurry was diluted with water to a concentration of 0.01 to 0.1% by mass and added dropwise to the hydrophilized carbon grid membrane. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.). It was confirmed that CNF1 to CNF7 were fine fibrous cellulose having a width of about 4 nm.

(Example 1)
CNF1 was diluted to 0.4% by mass, and 1 g of calcium chloride as a concentrating agent was added to 100 mL of the diluted solution for gelation. After filtration, it was squeezed with a filter paper to obtain a concentrate having a solid content concentration of 21.4% by mass. After immersing the concentrate in 100 mL of a 0.1 N hydrochloric acid aqueous solution for 30 minutes, 2 g of isopropanol and 2 g of a 6% sodium hydroxide aqueous solution were added, mixed well with a spatula, and then filtered to a solid content concentration of 23.0% by mass. A concentrate was obtained. 2 g of isopropanol and 2 g of ion-exchanged water were added to the concentrate, mixed well with a spatula, and then filtered to obtain a concentrate having a solid content concentration of 26.7%. The resulting concentrate was placed in an oven set at 60 ° C. and heated for 45 minutes. The solid content concentration of the obtained concentrate was 98.9% by mass.

The obtained concentrate was treated at 500 rpm for 15 minutes using a ball mill P-6, a planet-type ball mill manufactured by Fritsch, with a ball diameter of 5 mm, to obtain powder particles.
The powder or granular material was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirred TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 5 minutes to prepare a 0.4% by mass aqueous solution.

(Example 2)
Powder granules in the same manner as in Example 1 except that the concentrate obtained in Example 1 was treated with a mixer (BM-RE08-HA, manufactured by Zojirushi) for 1 minute instead of being treated with a ball mill. Got Further, a 0.4% by mass aqueous solution was prepared in the same manner as in Example 1.

(Example 3)
Powders and granules were obtained in the same manner as in Example 1 except that CNF2 was used instead of CNF1 in Example 1. Further, a 0.4% by mass aqueous solution was prepared in the same manner as in Example 1.

(Example 4)
Powders and granules were obtained in the same manner as in Example 1 except that CNF3 was used instead of CNF1 in Example 1. Further, a 0.4% by mass aqueous solution was prepared in the same manner as in Example 1.

(Example 5)
CNF1 was diluted to 0.4% by mass, and 1 g of calcium chloride as a concentrating agent was added to 100 mL of the diluted solution for gelation. After filtration, it was squeezed with a filter paper to obtain a concentrate having a solid content concentration of 3.4% by mass. The concentrate is immersed in 100 mL of a 0.1 N hydrochloric acid aqueous solution for 30 minutes, 2 g of isopropanol and 2 g of a 6% sodium hydroxide aqueous solution are added, mixed well with a spatula, and then filtered to a solid content concentration of 4.2% by mass. A concentrate was obtained. 2 g of isopropanol and 2 g of ion-exchanged water were added to the concentrate, mixed well with a spatula, and then filtered to obtain a concentrate having a solid content concentration of 5.2%.
The obtained concentrate was treated with a mixer (BM-RE08-HA, manufactured by Zojirushi) for 1 minute to obtain a powder or granule.
The powder or granular material was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirred TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 5 minutes to prepare a 0.4% by mass aqueous solution.

(Example 6)
The concentrate having a solid content concentration of 5.2% obtained in Example 5 was dried for 10 minutes to obtain a concentrate having a solid content concentration of 14.6%. A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 5.

(Example 7)
The concentrate having a solid content concentration of 5.2% obtained in Example 5 was dried for 20 minutes to obtain a concentrate having a solid content concentration of 26.8%. A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 5.

(Example 8)
The concentrate having a solid content concentration of 5.2% obtained in Example 5 was dried for 30 minutes to obtain a concentrate having a solid content concentration of 40.1%. A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 5.

(Example 9)
The concentrate having a solid content concentration of 5.2% obtained in Example 5 was dried for 35 minutes to obtain a concentrate having a solid content concentration of 55.9%. A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 5.

(Example 10)
The concentrate having a solid content concentration of 5.2% obtained in Example 5 was dried for 40 minutes to obtain a concentrate having a solid content concentration of 72.5%. A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 5.

(Example 11)
CNF1 was diluted to 0.4% by weight. To 100 mL of the diluted solution, 200 mL of isopropanol was added, gelled, and filtered with a filter paper. 200 mL of isopropanol was added to the filtered gel, mixed, and then filtered by filter paper. The filtered gel was squeezed with filter paper. The resulting concentrate was placed in an oven set at 60 ° C. and heated for 45 minutes. The obtained concentrate was treated at 500 rpm for 15 minutes using a ball mill P-6, a planet-type ball mill manufactured by Fritsch, with a ball diameter of 5 mm, to obtain powder particles.
The powder or granular material was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirred TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 5 minutes to prepare a 0.4% by mass aqueous solution.

(Example 12)
A powder and granules and a 0.4% by mass aqueous solution were prepared in the same manner as in Example 11 except that a 2.0% by mass CNF1 diluted solution was used.

(Comparative Example 1)
CNF1 was diluted to 0.4% by mass, and 1 g of calcium chloride as a concentrating agent was added to 100 mL of the diluted solution for gelation. After filtration, it was squeezed with a filter paper to obtain a concentrate having a solid content concentration of 21.4% by mass. After immersing the concentrate in 100 mL of a 0.1 N hydrochloric acid aqueous solution for 30 minutes, 2 g of isopropanol and 2 g of a 6% sodium hydroxide aqueous solution were added, mixed well with a spatula, and then filtered to a solid content concentration of 23.0% by mass. A concentrate was obtained. 2 g of isopropanol and 2 g of ion-exchanged water were added to the concentrate, mixed well with a spatula, and then filtered to obtain a concentrate having a solid content concentration of 26.7%. The resulting concentrate was placed in an oven set at 60 ° C. and heated for 45 minutes. The solid content concentration of the obtained concentrate was 98.9% by mass.

The concentrate was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirred TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 5 minutes to prepare a 0.4% by mass aqueous solution.

(Comparative Example 2)
CNF1 was diluted to 0.4% by mass, 100 mL of the diluted solution was placed in a Teflon (registered trademark) petri dish, and dried in an oven at 60 ° C. until it was completely dried.
The obtained concentrate was treated at 500 rpm for 15 minutes using a ball mill P-6, a planet-type ball mill manufactured by Fritsch, with a ball diameter of 5 mm, to obtain powder particles.
The powder or granular material was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirred TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 5 minutes to prepare a 0.4% by mass aqueous solution.

The table below shows the results of the following measurements and evaluations of the concentrates prepared in each Example and each Comparative Example.

(Measurement of cumulative median diameter)
The particle size of the powder or granular material is measured using a laser diffraction / scattering type particle size distribution measuring device Microtrac3300EXII (manufactured by Nikki So Co., Ltd.), and the cumulative curve is obtained with the total volume of the powder or granular material as 100%. The cumulative median diameter (μm) was determined by calculating the particle size at the point where it was 50%.

(Measurement of volume average diameter)
The volume average diameter (μm) was determined by measurement using a laser diffraction / scattering type particle size distribution measuring device Microtrac 3300EXII (manufactured by Nikkiso Co., Ltd.).
(Measurement of number average diameter)
The number average diameter (μm) was determined by measurement using a laser diffraction / scattering type particle size distribution measuring device Microtrac 3300EXII (manufactured by Nikkiso Co., Ltd.).
(Measurement of area average diameter)
The area average diameter (μm) was determined by measurement using a laser diffraction / scattering type particle size distribution measuring device Microtrac 3300EXII (manufactured by Nikkiso Co., Ltd.).
(Measurement of specific surface area)
The specific surface area was determined by measurement using a laser diffraction / scattering type particle size distribution measuring device Microtrac 3300EXII (manufactured by Nikkiso Co., Ltd.).

(Measurement of bulk density)
The bulk density of the powder or granular material obtained in each Example and each Comparative Example was measured using an angle of repose measuring device (AS ONE). 100 ml of powder or granular material was charged into the chute of the angle of repose measuring device, the chute mouth was opened, the powder or granular material was dropped to the lower part, and the container (full volume ∨ = 50 ml) installed below was filled with the powder or granular material. Next, the raised portion of the shavings was cut horizontally to fill the volume. The mass of the powder or granular material remaining in the container was weighed, and the bulk density (g / ml) was calculated from the following formula.
Bulk density (g / ml) = mass of powder (g) / volume of powder (ml)

(Measurement of angle of repose)
The angle of repose of the powder or granular material obtained in each Example and each Comparative Example was measured using an angle of repose measuring device (AS ONE). 100 ml of powder or granular material was charged into the chute of the angle of repose measuring device, the chute mouth was opened, and the powder or granular material was dropped to the lower part. The angle between the slope of the powder and the horizontal plane after the fall was measured and used as the angle of repose.

(Measurement of haze value)
The concentrates prepared in each Example and each Comparative Example were added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirring TK Robomics, manufactured by Tokushu Kagaku Kogyo) at 1500 rpm for 5 minutes to 0.4% by mass. An aqueous solution (also called a redispersion solution) was prepared.
The haze of the 0.4% by mass dispersion liquid is put into a glass cell for liquid (manufactured by Fujiwara Seisakusho, MG-40, backlit path) having an optical path length of 1 cm, and the haze meter (Murakami color) conforms to JIS standard K7136. It was measured using "HM-150") manufactured by Technical Research Institute. The zero point measurement was performed with ion-exchanged water contained in the glass cell.

(Dispersity evaluation)
The concentrate prepared in each Example and each Comparative Example was added to 100 mL of ion-exchanged water, and the mixture was stirred with a disperser (stirring TK Robomics, manufactured by Tokushu Kika Kogyo) at 1500 rpm for 30 seconds to obtain 0.4% by mass. An aqueous solution (also called a redispersion solution) was prepared.
Hydrophobicized titanium oxide (STV-455, manufactured by Titan Kogyo, Ltd.) was added in an amount of 1.0% by mass to 100 mL of the above 0.4% by mass aqueous solution, and then sufficiently stirred with a spatula for 1 minute. It was allowed to stand for 30 minutes, and it was observed whether the hydrophobic titanium oxide separated from the aqueous layer.
⊚: Hydrophobicized titanium oxide did not separate and settle, and remained stable in the aqueous solution.
◯: Hydrophobicized titanium oxide that was slightly separated or settled was present, but the uniformity was maintained as a whole.
X: Hydrophobicized titanium oxide particles are precipitated or present on the water surface and separated from the water layer.

Claims (10)

A fine fibrous cellulose-containing material having a fine fibrous cellulose content of 5% by mass or more, which is powdery and has a cumulative medium diameter D50 of 50 μm or more and 1.2 mm or less, and is a fine fibrous cellulose. the average fiber width Ri 1~1000nm der, fine fibrous cellulose having an ionic substituent, microfibrous cellulose-containing material. The fine fibrous cellulose-containing material according to claim 1, wherein the haze value of the sample below is 20% or less: However, the sample has a solid content concentration of 0.4% by mass of the fine fibrous cellulose-containing material. This is a sample added to pure water and stirred with a disperser at 1500 rpm for 5 minutes. The fine fibrous cellulose-containing product according to claim 1 or 2, wherein the specific surface area is 0.005 m ² / cm ³ or more and 0.5 m ² / cm ^{3 or less.} The fine fibrous cellulose-containing product according to any one of claims 1 to 3, wherein the angle of repose is 4 to 50 °. The fine fibrous cellulose-containing product according to any one of claims 1 to 4, wherein the bulk density is 0.10 to 0.50 g / ml. The fine fibrous cellulose-containing product according to any one of claims 1 to 5 , further comprising an organic solvent. The fine fibrous cellulose-containing product according to claim 6 , wherein the organic solvent is isopropyl alcohol. The fine fibrous cellulose-containing product according to any one of claims 1 to 7 , further comprising water. The fine fibrous cellulose-containing product according to any one of claims 1 to 8 , wherein the fine fibrous cellulose has a phosphoric acid group. The fine fibrous cellulose-containing product according to any one of claims 1 to 9 , wherein the amount of the phosphoric acid group in the fine fibrous cellulose is 0.5 mmol / g or more.

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